Tissue engagement devices, systems, and methods

ABSTRACT

A method can include engaging the pericardium of a patient at two engagement positions of the pericardium. The method can further include moving the two engagement positions of the pericardium away from each other to tension a portion of the pericardium. The method can further include advancing an access device through the tensioned portion of the pericardium to introduce the access device into the pericardial space of the patient. Other and further methods are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/361,312, titled TISSUE ENGAGMENT DEVICES, SYSTEMS, AND METHODS, whichclaims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional PatentApplication No. 62/260,212, titled TISSUE ENGAGEMENT DEVICES, SYSTEM,AND RELATED METHODS, filed on Nov. 25, 2015; the entire contents of eachof the foregoing applications are hereby incorporated by referenceherein.

TECHNICAL FIELD

The present disclosure relates generally to systems, devices and methodsfor providing access to a region beneath a tissue layer. Morespecifically, the present disclosure relates to devices and methods foraccessing the space beneath a tissue layer, which space may be betweenthe tissue layer and an underlying structure (e.g., the pericardialspace).

BRIEF DESCRIPTION OF THE DRAWINGS

The written disclosure herein describes illustrative embodiments thatare non-limiting and non-exhaustive. Reference is made to certain ofsuch illustrative embodiments that are depicted in the figures, inwhich:

FIG. 1 is a perspective view of an embodiment of a tissue engagementsystem;

FIG. 2 is a perspective view of an embodiment of a tunneling system thatincludes an embodiment of a tunneler cannula and an embodiment of anobturator, wherein the depicted tunneling system can be a subset of thetissue engagement system of FIG. 1;

FIG. 3 is a perspective view of an embodiment of a tissue engagementsystem that includes the tunneler cannula of FIG. 2 and an embodiment ofa tissue engagement device, wherein the depicted tunneling system can bea subset of the tissue engagement system of FIG. 1;

FIG. 4A is an exploded perspective view of the tissue engagement deviceof FIG. 3;

FIG. 4B is an enlarged perspective view of a distal portion of anembodiment of an engagement element;

FIG. 5A is an enlarged partial perspective view of a distal portion ofthe tissue engagement device positioned within a distal portion of thetunneler cannula;

FIG. 5B is an enlarged partial perspective view, such as that of FIG.5A, that depicts the distal portion of the tissue engagement deviceadvanced past a distal end of the tunneler cannula, wherein the tissueengagement device is in a fully retracted or unactuated state in whichengagement arms and an access device are retracted;

FIG. 5C is an enlarged partial perspective view, such as that of FIGS.5A and 5B, that depicts the tissue engagement device in a partiallydeployed state in which the engagement arms are deployed and the accessdevice remains retracted;

FIG. 5D is an enlarged partial perspective view, such as that of FIG.5A-5C, that depicts the tissue engagement device in a fully deployedstate in which the engagement arms are deployed and the access device isdeployed;

FIG. 6A is an exploded perspective view of a housing and an actuationinterface portion of an actuation mechanism of the tissue engagementdevice, which may also be referred to as an interlock mechanism;

FIG. 6B is a further perspective view of an upper component of thehousing;

FIG. 6C is a further perspective view of the actuation interface;

FIG. 6D is a perspective view of an embodiment of a gate portion of theactuation mechanism that depicts the gate in a closed state;

FIG. 6E is another perspective view of the gate that depicts the gate inan open state;

FIG. 6F is an exploded perspective view of a portion of an embodiment ofan actuator that includes an embodiment of an actuation cannula and anembodiment of an actuation shuttle in an uncoupled state;

FIG. 6G is an exploded perspective view of an embodiment of an accessassembly that includes an embodiment of an access device and anembodiment of a hub in an uncoupled state;

FIG. 7A is a cross-sectional view of the tissue engagement device alongthe view line 7A-7A in FIG. 1, as coupled with the tunneler cannula(also shown in cross-section), that depicts the actuation device in afully retracted configuration and corresponds with the distal viewdepicted in FIG. 5B;

FIG. 7B is another cross-sectional view of the tissue engagement devicesuch as that of FIG. 7A, that depicts the actuation device in apartially deployed state, with the actuator advanced distally to anintermediate position;

FIG. 7C is another cross-sectional view of the tissue engagement device,such as that of FIGS. 7A and 7B, that depicts the actuation device in apartially deployed state, with the actuator advanced a distal-mostposition;

FIG. 7D is another cross-sectional view of the tissue engagement device,such as that of FIGS. 7A-7C, that depicts the actuation device in afully deployed state, with the actuator in the distal-most orientationand the access assembly advanced distally to deploy the access device;

FIG. 7E is another cross-sectional view of the tissue engagement device,such as that of FIGS. 7A-7D, that depicts the actuation device in apartially deployed state again, with the access assembly having beenwithdrawn distally to a configuration that permits retraction of theactuator;

FIG. 8A depicts an early stage of an illustrative method for accessing aregion beneath a tissue layer, in which the tissue engagement system ofFIG. 1 can be used;

FIG. 8B depicts another stage of the illustrative method in which theobturator contacts the tissue layer;

FIG. 8C depicts another stage in which the obturator is being removedfrom the tunneler cannula;

FIG. 8D depicts another stage in which the tissue engagement device isadvanced through the tunneler cannula;

FIG. 8E depicts another stage in which the tissue engagement device isin the fully retracted configuration, such as that of FIGS. 5B and 7A,with distal tips of engagement arms positioned at the tissue layer;

FIG. 8F depicts another stage in which the tissue engagement device isin the partially deployed state, such as that of FIG. 7B, with theactuator advanced distally to an intermediate position to embed theengagement arms in the tissue layer;

FIG. 8G depicts another stage in which the tissue engagement device isin the further partially deployed state, such as that of FIGS. 5C and7C, with the actuator advanced to the distal-most position to furtherembed the engagement arms in the tissue layer;

FIG. 8H depicts another stage in which the tissue engagement device isin the same configuration as that depicted in FIG. 8G and in which thesystem is drawn proximally to enlarge a space between the tissue layerand an underlying structure;

FIG. 8I depicts another stage in which the tissue engagement device hasbeen moved to the fully deployed state, such as that of FIGS. 5D and 7D,in that both the actuator and the access device have been advanceddistally; the access device has pierced the tissue layer to provideaccess to the space between the tissue layer and the underlyingstructure;

FIG. 8J depicts another stage in which the tissue engagement deviceremains in the fully deployed state and a distal end of a guidewire hasbeen advanced through the access device into the space between thetissue layer and the underlying structure;

FIG. 8K depicts another stage in which the tissue engagement device hasbeen returned to the partially deployed state, such as that of FIGS. 5Cand 7C, in that the actuator remains fully deployed and the accessassembly has retracted;

FIG. 9 is a side elevation view of an embodiment of an engagementelement during an early stage of manufacture;

FIG. 10A is a further side elevation view of the engagement elementafter manufacture of engagement arms;

FIG. 10B is a top plan view of the engagement element after manufactureof the engagement arms;

FIG. 11A is a perspective view of the engagement element in aconstrained state, such as may be provided by a sheath—not shown in thepresent view (but see, e.g., FIG. 5B);

FIG. 11B is a side elevation view of the engagement element in theconstrained state;

FIG. 11C is a top plan view of the engagement element in the constrainedstate;

FIG. 11D is a front elevation view of the engagement element in theconstrained state;

FIG. 12A is a front elevation view of the engagement element in theconstrained state when actuated from within, such as via an actuationcannula—not shown in the present view (but see, e.g., FIG. 5C);

FIG. 12B is a perspective view of the engagement element in theconstrained state when actuated from within, such as via an actuationcannula—not shown in the present view (but see, e.g., FIG. 5C);

FIG. 13 is a front elevation view (e.g., an end-on view directedproximally) of a distal end of an embodiment of an engagement device ina fully deployed configuration;

FIG. 14A is a perspective view of a distal end of an embodiment of aneedle suitable for use with embodiments of engagement devices disclosedherein;

FIG. 14B is a side elevation view of the distal end of the needle ofFIG. 14A;

FIG. 15 is a perspective view of another embodiment of a tissueengagement system that is depicted in an fully retracted state;

FIG. 16 is another perspective view of the tissue engagement system ofFIG. 15 that depicts the system in a partially deployed state in whichengagement arms have been extended;

FIG. 17 is another perspective view of the tissue engagement system ofFIG. 15 that depicts the system in a fully deployed state in whichengagement arms have been extended and an access device has beendeployed;

FIG. 18 is an enlarged perspective view of a distal portion of thetissue engagement system in the fully deployed state of FIG. 17;

FIG. 19 is a front elevation view (e.g., an end-on view directedproximally) of a distal end of the tissue engagement system in the fullydeployed state of FIG. 17; and

FIG. 20 is a top plan view of the distal end of the tissue engagementsystem in the fully deployed state that depicts the system havingengaged a tissue layer via deployed arms and pierced the tissue layervia the access device to provide access to a region below the tissuelayer.

DETAILED DESCRIPTION

Known systems, devices and methods for providing access to a regionbeneath a tissue layer, or more particularly, for accessing a space(e.g., the pericardial space or pericardial cavity) between a tissuelayer (e.g., the parietal pericardium) and an underlying structure(e.g., the epicardium), suffer from a variety of drawbacks. In the fieldof cardiac medicine, for example, minimally invasive therapies fortreating conditions at the heart's surface, or epicardium, have beendeveloped or contemplated. Example treatments include epicardialablation, left atrial appendage ligation, lead placement, and drugdelivery. An important element of these procedures is safely gainingaccess to the pericardial space through the pericardium, which is athin, protective, multi-layer membrane surrounding the heart. Theoutermost layer is the fibrous pericardium and the inner surface facingthe pericardial space is a serous membrane called the parietal layer orpericardium. Opposing the parietal pericardium is another serousmembrane called the visceral layer, which forms the outer surface of theepicardium. The pericardial space between the visceral and parietallayers is a thin film of serous fluid that provides lubrication. Becauseof its close proximity to the epicardium, creating an access portthrough the very thin pericardium can be difficult without injuring theunderlying epicardium, heart muscles (myocardium tissue) and otherstructures such as blood vessels and nerves. The movement of the beatingheart, breathing motions, presence of fatty surface tissue on theexternal surface of the fibrous pericardium, and toughness of thepericardium are some of the additional factors that can increase accessdifficulty.

Non-minimally invasive procedures for accessing the pericardial spaceare considered surgical methods and can use a thorascope to create anopening in the pericardium called a pericardial window. One acceptedminimally invasive method for accessing the pericardial space betweenthe pericardium and epicardium for purposes other than drainingeffusions (pericardiocentesis) involves carefully inserting a needlewith fluoroscopic guidance. This procedure, which has been used for manyyears and is still performed at present, employs a commerciallyavailable Tuohy needle (typically 17 gauge or 18 gauge) thataccommodates a standard 0.035 inch (8.9 millimeter) guide wire. Otherepicardial access procedures are performed with a 21 gauge micropunctureneedle which, because of the much smaller diameter, is more benign tounintended heart puncture, but very difficult to use because it is lessstiff and requires exchanging to a larger, more stable 0.035 inch (8.9millimeter) guide wire. Using either needle type requires a high degreeof skill and practice, and can be very time-consuming, and thereforethis procedure has not been widely adopted, limiting the use of emergingepicardial therapies.

These and other known devices and procedures suffer from a variety ofdrawbacks, as will be apparent from the disclosure herein. Theselimitations can be ameliorated or eliminated by embodiments disclosedhereafter.

The present disclosure relates generally to tissue engagement devices,systems, and methods. In particular, certain embodiments disclosedherein can be used for creating or enlarging a space between two tissuelayers and, additionally, can be used to access the space.

For purposes of illustration, much of the disclosure herein pertains tocreating or enlarging the pericardial space and also accessing thisspace. Certain devices can engage the pericardium (i.e., the parietalpericardium), which can be pulled away from the heart, or statedotherwise, away from underlying tissue (e.g., the visceral pericardiumor epicardium) to expand the pericardial cavity, which may also bereferred to as the pericardial space. Enlarging the pericardial space inthis manner can reduce the risk of puncturing the underlying tissue(e.g., the epicardium) when a needle is advanced through the pericardiumto provide access to this space. Numerous procedures can benefit fromproviding access to the pericardial space in this manner, such as, forexample, collection of pericardial fluid, pericardial biopsy, diagnosticand therapeutic agent delivery, placement of electrical leads,electrophysiology mapping and/or ablation, angioplasty, restenosisreduction, coronary vessel stent placement, coronary vessel bypassgrafting, etc. Disclosures provided herein in the context of pericardialaccess, however, should not be construed as limiting, as other orfurther embodiments can be used for engaging other tissue layers andproviding access to other spaces between tissue layers in a patient.

FIG. 1 is a perspective view of an embodiment of a tissue engagementsystem 100. As more fully described hereafter, the tissue engagementsystem 100 can be used to engage a tissue layer and to pierce the tissuelayer to provide access to a region beneath the tissue layer. Certainembodiments can be particularly well suited for engaging and piercingtissue layers that are relatively thin and/or are closely situated to anunderlying structure. For example, some embodiments are well suited forengaging and piercing the pericardium, and can be configured to do sowithout contacting or damaging the underlying epicardium. Other featuresand advantages of various embodiments will be apparent from thedisclosure that follows.

In the illustrated embodiment, the tissue engagement system 100 includesa tunneling system 101 and a tissue engagement system 102. Statedotherwise, each of the tunneling system 101 and the tissue engagementsystem 102 is a subset of the tissue engagement system 100. In theillustrated embodiment, a tunneler cannula 110 is common to both thetunneling system 101 and the tissue engagement system 102. That is, thetunneler cannula 110 can be used with the tunneling system 101 to tunnela path to a target tissue layer, and can further be used with the tissueengagement system 102 in the subsequent engagement and piercing of thetarget tissue layer.

In addition to the tunneler cannula 110, the tunneling system 101includes an obturator 120, and the tunneling system 102 includes atissue engagement device 130. In the illustrated embodiment, each of theobturator 120 and the tissue engagement device 130 is configured to beselectively coupled with the tunneler cannula 110.

In some embodiments, the tissue engagement system 100 is provided as akit 103. For example, the tunneler cannula 110, the obturator 120, andthe tissue engagement device 130 can be assembled as a set anddistributed together, such as in unitary sterile packaging. In otherembodiments, the kit 103 may exclude one or more of the obturator 120 orthe tunneler cannula 110. In other instances, one or more of thetunneler cannula 110, the obturator 120, or the tissue engagement device130 can be distributed separately.

With reference to FIG. 2, the tunneling system 101 is shown in greaterdetail In the illustrated embodiment, the tunneler cannula 110 includesa cannula, shaft, or tube 111 that defines a lumen 112.

The tunneler cannula 110 can further include a connector 113 at aproximal end of the tube 111. The connector 113 can be of any suitablevariety and can be configured to selectively couple/decouple thetunneler cannula 110 to/from the obturator 120. In the illustratedembodiment, the connector 113 comprises a female snap fitting 114 thatincludes two resilient prongs 115 a, 115 b that are configured to flexoutwardly relative to a longitudinal axis of the tunneler cannula 110. Aproximal end of each resilient prong 115 a, 115 b includes an inwardlydirected ridge 116 that can engage a complementary portion of theobturator 120. The illustrated snap fitting 114 includes a pair ofdiametrically opposed channels 117 (only one of which is shown in FIG.2). The channels 117 can facilitate flexion of the prongs 115 a, 115 b.In some embodiments, the tunneler cannula 110 can include one or moredepth markings 118 of any suitable variety.

The illustrated obturator 120 includes a rod 121 that is sized tosubstantially fill the lumen 112 of the tunneler cannula 110. Forexample, an outer diameter of the rod 121 can be slightly smaller thanan inner diameter of the tube 111 to permit the obturator 120 to bereadily inserted into and removed from the tube 111, while still fillingthe lumen 112 to prevent coring thereby as the tube 111 is advancedthrough tissue (e.g., soft or connective tissue) of a patient.

As used herein, the term “diameter” is used in its broadest sense, andincludes the definition of a straight line from one side of something tothe other side that passes through the center point, or the distancethrough the center of something from one side to the other. That is, theterm diameter does not necessarily imply a circular configuration.Although the drawings generally depict circular or cylindricalsymmetries, such as for the tube 111 and the rod 121, the presentdisclosure contemplates non-circular configurations. For example,various embodiments can have non-circular cross-sectional profiles suchas triangular, rectangular, polygonal, oval, etc. Unless otherwisespecified, the term “diameter” refers to the maximum diameter of a givenfeature, or portion thereof, as will be apparent from context.

The obturator 120 can include a dull or blunt tip 122 that may berounded at a distal end thereof. The tip 122 may have a sufficientlysteep pitch (e.g., be sufficiently sharp) to permit the obturator 120 tobe readily advanced through tissue. In some embodiments, the tip 122 is,nevertheless, sufficiently blunt to prevent inadvertent puncturing orperforation of a target tissue layer when the tip 122 presses againstthe target tissue layer. For example, in some embodiments, the tip 122may be readily advanced through tissue of a patient toward the heart ofthe patient (e.g., by application of about 2 or 3 pounds of force), butwhen the tip 122 comes into contact with the heart (e.g., thepericardium) with the same amount of force, the tip 122 is stoppedthereby and does not puncture the heart.

The obturator 120 can include a connector 123 that is configured to beselectively coupled with the connector 113 of the tunneler cannula 110.The illustrated connector 123 is a male snap fitting 124 that iscomplementary to the female snap fitting 114 of the tunneler cannula110. The snap fitting 124 includes an inclined or camming surface 125that spreads apart the prongs 115 a, 115 b until the ridges 116 arereceived into a groove 126 at a proximal end of the camming surface 125.Any other suitable connection interface between the obturator 120 andthe tunneler cannula 110 is contemplated.

In the illustrated embodiment, the obturator 120 includes a pair ofdiametrically opposed ridges 127, which may act as grips that can permitready twisting of the tunneling system 101 during a tunneling event. Theobturator 120 can include an enlarged base 128, which may besubstantially flat, which may facilitate application of distallydirected force to the tunneling system 101 during a tunneling event.

With reference to FIG. 3, the tissue engagement device 130 can includecoupling features similar or identical to those of the obturator 120.For example, in the illustrated embodiment, the tissue engagement device130 includes a connector 133 having a camming surface 135 and a groove136 that are the same as like-numbered, like-named features of theobturator. Accordingly, after a tunneling event, the obturator 120 canbe readily removed from the tunneler cannula 110 and replaced with thetissue engagement device 130.

The tissue engagement device 130 can include an elongated housing orsheath 131 that defines a lumen 132. In order to diminish the profile ofa distal portion of the tissue engagement system 102 that is inserted ina patient, the sheath 131 can have an outer diameter that is slightlysmaller than an inner diameter of the tube 111. Such an arrangement canpermit the sheath 131 to be readily inserted into and removed from thetube 111, while providing a large amount of space for components of thetissue engagement device 130 that are housed within the sheath 131. Invarious embodiments, an outer diameter of the sheath 131 can be nogreater than about 0.15, 0.10, or 0.09 inches (3.8, 2.5, or 2.3millimeters). In some embodiments, the outer diameter of the sheath 131is about 0.96 inches (2.4 millimeters).

A thickness of a sidewall of the sheath 131 may also be selected toprovide the sheath 131 with sufficient stiffness or rigidity to resistbending, while being narrow to provide a large amount of space for thecomponents housed within the sheath 131. In various embodiments, thethickness of the sidewall of the sheath 131 is no greater than about0.005, 0.004, or 0.003 inches (0.13, 0.1, 0.08 millimeters).

The sheath 131 may be formed of any suitable material. In someembodiments, the sheath 131 comprises stainless steel.

The tissue engagement device 130 can include an actuation mechanism 137that can include an actuation interface 138 via which a user can deploya portion of the tissue engagement device 130. In the illustratedembodiment, the actuation interface 138 comprises a button that can bepushed distally to actuate engagement arms or pulled proximally toretract the engagement arms after actuation, as further discussed below.The actuation mechanism 137 can further include an access assembly 139,which can be used to deploy an access device, such as a needle. In theillustrated embodiment, the access assembly 139 can be pushed distallyto deploy the needle and can be pulled proximally to retract the needleafter deployment, as discussed further below.

With reference to FIG. 4A, the actuation mechanism 137 of the tissueengagement device 130 can include a housing 140 within which variouscomponents are received. In the illustrated embodiment, the housing 140includes an upper shell 141 and a lower shell 142. The upper and lowershells 141, 142 can be secured to each other in any suitable fashion,including one or more of friction-fit engagement, snap-fit engagement,adhesive, welding (e.g., ultrasonic welding), etc.

Use of directional terms herein, such as “upper” and “lower,” aregenerally relative to the orientations depicted in the drawings. Suchdirectional terms are not necessarily intended to limit the possibleorientations of the devices or components. For example, in someinstances, a user may prefer to orient the upper shell 141 downwardly,and the lower shell upwardly 142, during use of the actuation mechanism.

In some embodiments, the assembled housing 140 can be sized to fitwithin the curvature of one or more curled, clenched, or gripped fingersof a user's hand. For example, an external width of the assembledhousing 140 can be no greater than about ½ inch, ⅝ inch, ¾ inch, 1 inch,or 1.5 inches (1.3, 1.6, 1.9, 2.5, or 3.8 centimeters). In someembodiments, the width is about ⅝ inches. In some embodiments, anexternal length of the assembled housing 140 can simultaneously contactup to 3 or up to 4 curled, clenched, or gripped fingers of one of auser's hands. Such a configuration can provide the user with a firmhandle on the housing 140 and can permit stable, reliable, and/orergonomic usage of the engagement device 130. In various embodiments, agripping region of the assembled housing (e.g., the substantiallyparallepiped central portion of the illustrated embodiment) can have alength that is no greater than about 2, 2.5, or 3 inches (5.1, 6.4, or7.6 centimeters). In some embodiments, the length is about 2.25 inches.

As further discussed hereafter, the actuation interface 138 can bemovably coupled with the housing 140. For example, in the illustratedembodiment, the actuation interface 138 can be configured to beselectively translated distally (for actuation) or proximally (forretraction). A location of the actuation interface 138 relative to thehousing 140 can be ergonomically designed for ease of use. In theillustrated embodiment, the actuation interface 138 is configured topass substantially through a center point of an upper surface of theupper shell 141. The actuation interface 138 may further be configuredto move approximately equal distances from the center point in each ofthe distal and proximal directions. Other suitable configurations arealso contemplated. The actuation interface 138 may be convenientlylocated for single-handed operation thereof. For example, in theillustrated embodiment, the housing can be gripped by multiple fingersof one hand of a user and the actuation interface 138 can be controlledby the thumb of that hand.

The lower shell 142 of the housing 140 can define the connector 133. Inthe illustrated embodiment, the sheath 131 is fixedly secured to theconnector 133 in any suitable manner. An engagement element 143 can bereceived within the lumen 132 of the sheath 131, and may be fixedlysecured to the connector 133 and/or the sheath 131. Stated otherwise,the engagement element 143 can be fixed relative to the sheath 131and/or relative to the housing 140. In the illustrated embodiment, aproximal end of the engagement element 143 is attached to a proximal endof the sheath 131.

FIG. 4B depicts a distal portion of the engagement element 143 ingreater detail. The engagement element 143 comprises a base 104, whichdefines the proximal portion of the engagement element 143. In theillustrated embodiment, the base 104 is a substantially tubular orcannular structure, and thus the base 104 may also be referred to as acannular base. The cannular base 104 defines a lumen 105. In theillustrated embodiment, an outer diameter of the base is slightlysmaller than an inner diameter of the sheath 131.

In the illustrated embodiment, a plurality of flexible arms 108 a, 108 bextend distally from a distal end of the base 104. The arms 108 a, 108 bmay also be referred to as tines or prongs. As further discussed below,the arms 108 a, 108 b may be integrally connected to the base 104, insome embodiments, or stated otherwise, the base 104 and the arms 108 a,108 b may be integrally formed from a unitary piece of material. Forexample, the arms 108 a, 108 b may be formed by cutting away (e.g.,laser cutting) portions of a tube (see FIG. 9) and then bending theremaining protrusions. In some embodiments, prior to insertion of theengagement element 143 into the sheath 131, the arms 108 a, 108 b mayretain a bent configuration that extends transversely outward beyond anouter perimeter of the base 104, such as, for example, the configurationdepicted in FIGS. 10A and 10B.

Each arm 108 a, 108 b can include a tissue engaging member 109 a, 109 bthat can embed within, pierce, or otherwise attach to a target tissuelayer. The tissue engaging members can each include a pointed element,such as an angled end, spike, or barb, that can pierce into the targettissue layer. In the illustrated embodiment, each tissue engaging member109 a, 109 b includes an angled distal end of the respective arm 108 a,108 b.

With reference again to FIG. 4A, the engagement device 130 can includean actuation member 145 that communicates movement of the actuationinterface 138 at a proximal end thereof to a distal end of the actuationmember 145. As further discussed below, the actuation member 145 can beconfigured to deploy the arms 108 a, 108 b of the engagement element143. In some embodiments, such as that illustrated in FIG. 4A, theactuation member 145 comprises a tube or cannula. Accordingly, theactuation member 145 may also be referred to as an actuation cannula.

Further, the illustrated embodiment includes a piercing member or accessdevice 147 that is configured to create an access opening through thetarget tissue layer when deployed. In the illustrated embodiment, theaccess device 147 is a needle. Any suitable needle or other piercingmember may be used. The actuation member 145 can be positioned withinthe lumen 132 of the sheath 131, and can be sized to slide or otherwisetranslate freely therein. The access device 147 can be positioned withinthe lumen 105 of the actuation member 145, and can be sized to slide orotherwise translate freely therein.

The actuation mechanism 137 can include multiple components that areconfigured to constrain operation of the tissue engagement device 130.In particular, in the illustrated embodiment, the actuation mechanism137 includes components that control the movement of the actuationmember 145 relative to the engagement element 143, and also relative tothe access device 147. Further, the actuation mechanism 137 includescomponents control the movement of the access device 147 relative to theactuation member 145 and the engagement element 143. In the illustratedembodiment, the actuation mechanism includes a gate 144 that is receivedwithin the lower shell 142 of the housing, a shuttle 146 that is coupledwith the actuation member 145, and a hub 149 that is coupled with theaccess device 147. At least a portion of each of these components ispositioned within the housing 140. Various features of these componentsand their functions are discussed further below with respect to FIGS.6A-7E. The access assembly 139 includes the hub 149 and the accessdevice 147. The actuation interface 138, the shuttle 146, and theactuation member 145 may be referred to collectively herein as anactuation assembly 148.

FIGS. 5A-5D depict the tissue engagement system 102 in variousoperational states, which can correspond with method steps for using thesystem 102. These figures depict a distal end of the assembledengagement system 102. Although illustrative examples for achieving theoperational states depicted in FIGS. 5A-5D can be achieve via theillustrated actuation mechanism 137, as described further below withrespect to FIGS. 6A-7E, it should be understood that any suitablesystems and methods for achieving the operational states discussed arecontemplated.

FIG. 5A depicts a distal portion of the tissue engagement device 130positioned within a distal portion of the tunneler cannula 110. The tube111 of the tunneler cannula is shown as the outermost tube. The outersurfaces of the sheath 131, the cannular base 104, the actuation member145, and the access device 147 are depicted in broken lines. This viewdepicts the compact configuration achieved by the nested, telescopic, orcoaxial arrangement of the tube 111, the sheath 131, the cannular base104, the actuation member 145, and the access device 147.

The arms 108 a, 108 b and the tissue engaging members 109 a, 109 b arealso identified in FIG. 5A. In this operational configuration of thetissue engagement system 102, the tissue engagement device 130 mayeither be in the process of being advanced distally toward or through adistal end of the tube 111 or retracted proximally through the tube 111.In either case, the pointed ends of the tissue engaging members 109 a,109 b are at an interior of the tube 111, or stated otherwise, arewithin the lumen 112. In this arrangement, the pointed ends cannotinadvertently contact tissue (i.e., tissue at an exterior of the tube111) during advancement through the tube 111 or retraction through thetube 111.

FIG. 5B depicts the distal end of the tissue engagement device 130advanced past a distal end of the tube 111 of the tunneler cannula 110.As with FIG. 5A, the tissue engagement device 130 is depicted in a fullyretracted or unactuated state. In the fully retracted state, neither thearms 108 a, 108 b nor the access device 147 is deployed. The illustratedconfiguration can represent a point in time after the system 102 hasbeen advanced to the target tissue layer and just before deployment ofthe arms 108 a, 108 b.

In the illustrated embodiment, the engaging members 109 a, 109 b of thearms 108 a, 108 b are positioned slightly external to a distal end ofthe sheath 131 when the tissue engagement device 130 is in the fullyretracted configuration. Stated otherwise, the engaging members 109 a,109 b are positioned distally relative to a distal end of the sheath131. The exposed pointed tips of the engaging members 109 a, 109 b mayreadily engage a target tissue layer upon contact therewith as thedistal end of the sheath 131 is advanced into contact with the targettissue layer. Indeed, in the illustrated embodiment, the pointed tipsare directed in a slightly distal direction, such that initial contactof the pointed tips with the target tissue layer as the engagementdevice 130 is advanced distally through the tunneler cannula 110 canurge the pointed tips into the target tissue layer. Further, due to theslight exposure of the pointed tips past the distal end of the sheath131, abutting contact of the distal end of the sheath 131 against thetarget tissue layer can provide tactile feedback to the user that thetissue layer has been initially engaged and that deployment of the arms108 a, 108 b can proceed.

Although the engaging members 109 a, 109 b in the illustrated embodimentextend in a longitudinal direction, or distally, beyond the distal tipof the sheath 131, the engaging members 109 a, 109 b are neverthelessrestrained to a low-profile configuration in which they either do notextend or do not significantly extend laterally outward beyond aperimeter of the sheath 131. For example, if the arrangement depicted inFIG. 5B were shown in an end-on view (directed proximally), similar tothe view depicted in FIGS. 11D and 13, the full perimeter of the distalend of the sheath 131 would be visible in situations where the engagingmembers 109 a, 109 b do not extend laterally outward beyond theperimeter. In this view, the engaging members 109 a, 109 b would appearto be interior to the perimeter. Stated otherwise, if an outer surfaceof the sheath 131 were projected distally beyond the distal end of thesheath 131, either all or substantially all (e.g., no less than 75percent) of the engaging members 109 a, 109 b would be encompassed orcircumscribed thereby. Such an arrangement can inhibit or avoidinteraction (e.g., snagging, tearing, etc.) between the engaging members109 a, 109 b and tissue that is positioned outside the perimeter of thesheath 131. This can be advantageous either during deployment of thetissue engagement device 130 beyond the distal end of the tunnelercannula 110 or during retraction of the engagement device 130 into thetunneler cannula 110.

The remainder of the arms 108 a, 108 b are positioned within the lumen132 of the sheath 131. As discussed further below, and as depicted inFIG. 5B, the arms 108 a, 108 b cross each other at a position that iswithin the lumen 132 and that is distal to a distal end of the actuationmember 145.

FIG. 5C depicts the tissue engagement system 102 after the arms 108 a,108 b have been deployed. In particular, the actuation member 145 hasbeen advanced distally beyond the position at which the arms 108 a, 108b crossed each other, thereby uncrossing the arms 108 a, 108 b anddeforming them from the undeployed configuration depicted in FIG. 5B.The actuation member 145 has forced a proximal portion of the arms 108a, 108 b into an annular region between an outer surface of theactuation member 147 and an inner surface of the sheath 131.

In the illustrated embodiment, the arms 108 a, 108 b are atdiametrically opposite sides of the device 130 (e.g., at opposite sidesof the cannular base 104). As further discussed below, deployment of thearms 108 a, 108 b moves the engaging members 109 a, 109 b insubstantially opposite directions. The engaging members 109 a, 109 bthus can embed within and/or apply tension to the target tissue layer insubstantially opposite directions. The arms 108 a, 108 b are in ahigh-profile configuration in which they extend laterally outwardlybeyond a perimeter of the sheath 131.

In the illustrated configuration, the tissue engagement device 130 is ina partially deployed state, in that the arms 108 a, 108 b are deployed,but the access device 147 remains retracted. Deployment of the arms 108a, 108 b clears the engaging members 109 a, 109 b away from the distalend of the actuation member 145 to provide an unobstructed passagewayfor deployment of the access device 147. Stated otherwise, in theconfiguration depicted in FIG. 5B, the arms 108 a, 108 b cover a distalend of the actuation member 145. Deployment of the arms 108 a, 108 beffectively uncovers the distal end of the actuation member 145 toprovide an access pathway for the access device 147.

As used herein, the term “cover” does not require direct contact againsta surface (e.g., the distal end of the actuation member 145), althoughsuch an arrangement is subsumed within this term. The term “cover” isused more broadly herein, and includes situations of obstruction withoutdirect contact. For example, if the arrangement depicted in FIG. 5B wereshown in an end-on view (directed proximally), similar to the viewdepicted in FIG. 13, rather than perspective, much of the opening in thedistal end of the actuation member 145 would be obstructed from view bythe arms 108 a, 108 b. Of more pertinence, viewed in the oppositedirection—namely, from the perspective of the distal end of the accessdevice 147, the distal opening of the actuation member 145 would appearto be obstructed. Stated otherwise, if an inner surface of the actuationmember 145 that defines the distal opening of the actuation member 145were projected distally beyond the distal end of the actuation member145, the arms 108 a, 108 b would be encompassed or circumscribedthereby.

In some embodiments, the actuation mechanism 137 can prevent deploymentof the access device 147 prior to deployment of the arms 108 a, 108 bvia the actuation member 145. This can be a safety measure to ensurethat the user does not inadvertently partially deploy the arms 108 a,108 b by moving the access device 147 distally past the arms. That is,because the outer diameter of the access device 147 is only slightlysmaller than the outer diameter of the actuation member 145, deploymentof the access device 147 prior to deployment of the actuation member 145could extend the engaging members 109 a, 109 b laterally outwardly to arelatively high-profile configuration, though potentially not quite aswide or as high-profile an arrangement as can be achieved by deploymentof the actuation member 145.

FIG. 5D depicts the tissue engagement device 130 in a fully deployedstate. In particular, the engagement arms 108 a, 108 b are deployed andthe access device 147 is also deployed. The access device 147 has beenadvanced distally through the actuation member 145 and beyond the distalend thereof.

In some embodiments, the actuation mechanism 137 can prevent theactuation member 145 from retracting the engagement arms 108 a, 108 bunless the access device 147 is first retracted. This can serve as asafety precaution, as retraction of the actuation member 145 withoutfirst retracting the access device 147 could leave the arms 108 a, 108 bin a partially deployed state. For example, in the illustratedembodiment, the access device 147 has an outer diameter that is slightlysmaller than an outer diameter of the actuation member 145. Thus, if theactuation member 145 were to be withdrawn while the access device 147 isin the deployed state, the resilient arms 108 a, 108 b would begin toreturn to the low-profile configuration upon retraction of the actuationmember 145, but would be prevented from reaching this configuration byinstead coming into contact with the outer surface of the access device147. The user could potentially think that the arms 108 a, 108 b hadbeen fully retracted at this stage, due to the retraction of theactuation member 145, and could withdraw the tissue engagement device130 with the arms 108 a, 108 b in the partially deployed state. Distalmovement of the tissue engagement device 130 in this state couldpotentially damage the target tissue layer, overlying tissue, and/or theengagement device 130 itself.

In certain embodiments, a method of retracting the system 102 from apatient can follow the stages depicted in FIGS. 5A-5D in reverse order.For example, beginning with the configuration depicted in FIG. 5D, theaccess device 147 can be retracted to the orientation depicted in FIG.5C. Thereafter, the actuation member 145 can be retracted to theorientation depicted in FIG. 5B. In certain embodiments, due toresilience of the arms 108 a, 108 b, this retraction of the actuationmember 145 will also case the arms 108 a, 108 b to naturally orautomatically return from the deformed condition in FIG. 5C to theconfiguration depicted in FIG. 5B. Thereafter, the tissue engagementdevice 130 can be withdrawn through the lumen of the tunneling cannula110, as depicted in FIG. 5A.

FIGS. 6A-6G depict an illustrative embodiment of the actuation mechanism137 for the tissue engagement device 130. As previously mentioned, othersuitable mechanisms are also contemplated and are within the scope ofthe present disclosure. The illustrated actuation mechanism 137 iscapable of preventing two potentially undesirable configurations of thetissue engagement device 130. In particular, the actuation mechanism 137is configured to prevent the access device 147 from being deployed priorto deployment of the arms 108 a, 108 b via the actuation member 145,which can avoid the potentially undesirable results for such aconfiguration discussed above. The illustrated actuation mechanism 137is further configured to prevent retraction of the actuation member 145and the resultant retraction of the arms 108 a, 108 b, which can avoidthe potentially undesirable results for such a configuration discussedabove. The illustrated actuation mechanism 137 may be referred to as adual interlock system or as a locking mechanism. Stated otherwise, theactuation mechanism 137 can serve as a lock to prevent a firstpotentially undesirable configuration of the tissue engagement device130, and can further serve as a lock to prevent a second potentiallyundesirable configuration of the tissue engagement device 130. In otherembodiments, an interlock device may prevent only one of the potentiallyundesirable configurations. In still other embodiments, the actuationmechanism 137 may not function as an interlock device for eitherpotentially undesirable configuration.

FIG. 6A depicts an exploded perspective view of an embodiment of thehousing 140, which includes the upper shell 141 and the lower shell 142.The lower shell 142 can include the connector 133 at a distal endthereof, as previously described. The connector 133 can define a lumen133 a through which the actuation member 145 and the access device 147can pass for advancement to a deployed state or retraction to aretracted state.

With reference to FIGS. 6A and 6B, the lower shell 142 can define acavity 150 a into which certain components of the actuation mechanism147, or portions thereof, can be received. The upper shell 141 likewisedefines a cavity 150 b into which certain components or portions thereofcan be received. When the upper and lower shells 141, 142 are coupled toeach other, the cavities 150 a, 150 b define a unitary volume of space.

The dual interlock property of the illustrated embodiment of theactuation mechanism 137 generally operates on two levels or planes. Theupper level is generally defined by a lower portion of the upper shell141. The lower level is defined by the lower shell 142. For example, thelower shell 142 includes an actuator stop 151, which is a roundedprotrusion that extends upwardly from a substantially flat base wall ofthe lower shell 142. As further discussed below, the actuator stop 151is configured to interact with a component in the lower level.

The lower shell 142 further includes a coupling protrusion 152 that isconfigured to connect with the gate 144, as further discussed below. Aproximal end of the lower shell 142 can include a key slot region 155 adefined by a keying surface 153 a. A proximal end of the upper shell 141likewise can include a key slot region 155 b defined by a keying surface155 b. When the upper and lower shells 141, 142 are coupled to eachother, the key slot regions 155 a, 155 b define a unitary key slot, andthe keying surfaces 153 a, 153 b cooperate to maintain a fixedrotational orientation of the hub 149 as portions thereof are advanceddistally into or retracted proximally from the housing 140.

The upper shell 141 defines a recess 156 within which the actuationinterface 138 can translate forward or backward. The upper shell 141further defines a longitudinal channel 157 along which the actuationinterface 138 can be translated forward or backward. The upper shell 141also includes a transverse channel 158 through which a portion of theactuation interface 138 can be advanced.

With reference to FIG. 6B, the upper shell 141 defines a pair of stops159 a, 159 b that can selectively prevent proximal movement of theshuttle 146, as further described below. The stops 159 a, 159 b residewithin the upper level along which the dual interlock mechanismoperates.

With reference to FIG. 6A, the illustrated actuation interface 138 isformed as a button 160, which may also be referred to as a slider. Theillustrated button 160 is particularly well suited for actuation via athumb of a user while the housing 140 is held by fingers of the hand,although other actuation grips are possible. The button 160 includes aproximal surface 161 that is contoured to receive a thumb tip of a user.The proximal surface 161 rises in a distal direction toward a grip 163,which can provide traction for the user. While any suitable griparrangement is contemplated, the illustrated grip includes transverselydirected grooves. A distal surface 162 drops steeply from the apex. Theuser can readily grip the apex and/or upper portions of the distalsurface 162 to apply rearward directed force for retraction of theactuation assembly 148.

With reference to FIG. 6C, the button 160 can include a longitudinalguide 164 that is sized to slide within the longitudinal channel 157 ofthe upper shell 141. The button 160 can further include a lateralretainer or transverse bar 165 that cooperates with a bottom surface ofthe button 160 to define a channel 166 on either side of the guide 164.The channels 166 can receive a portion of the upper shell 141 thatborders the longitudinal channel 157.

FIGS. 6D and 6E depict the gate 144 in two different operational states.In FIG. 6D, the gate 144 is closed, whereas the gate 144 is open in FIG.6E. The gate 144 is positioned within the lower shell 142. Accordingly,the gate 144 operates in the lower level of the dual interlockmechanism.

The gate 144 includes a base 170 from which two resilient arms 171 a,171 b extend in the proximal direction. The base 170 defines an opening172 sized to receive the coupling protrusion 152 of the lower shell 142to connect the gate 144 to the lower shell 142. The distal ends of thearms 171 a, 171 b cooperate with an inner surface of the base 170 todefine a receptacle 173. When the gate 144 is coupled to the lower shell142, the actuator stop 151 resides within the receptacle 173.

Generally central portions of the arms 171 a, 171 b include inwardlyprojecting camming surfaces 174 a, 174 b, respectively. The cammingsurfaces 174 a, 174 b are configured to interact with a portion of theshuttle 146 to selectively open the gate 144, as further describedbelow.

The proximal ends of the arms 171 a, 171 b include stops 175 a, 175 bthat are configured to abut a portion of the hub 149 to prevent distalmovement of the hub 149 when the gate 144 is in the closed state of FIG.6D. When the gate 144 is in the open state of FIG. 6E, the stops 175 a,175 b are separated from each other to define a passageway 176 throughwhich the portion of the hub 149 can pass in the distal direction.

FIG. 6F depicts a portion of the actuator 148, which includes theactuation member 145 and the shuttle 146. As previously mentioned, theactuator 148 further includes the actuation interface 138.

As previously mentioned, in the illustrated embodiment, the actuationmember 145 is a cannula that defines a lumen 180. The lumen 180 is sizedto permit passage of the access device 147. A proximal end of theactuation member 145 can be coupled to a body 181 of the shuttle 146 inany suitable manner.

The shuttle 146 includes a pair of upwardly projecting sidewalls 182that cooperate to define a longitudinal channel 183 and a lateralchannel 187. The channels 183, 187 are sized to receive the longitudinalguide 164 and the transverse bar 165 that project downwardly from thebutton 160.

With reference to FIGS. 6A-6C and 6F, in coupling the button 160 withthe shuttle 146 and the upper shell 141 of the housing 140, thelongitudinal guide 164 and the transverse bar 165 are inserted throughthe longitudinal channel 157 and the transverse channel 158 of the uppershell 141 and into the longitudinal channel 183 and the lateral channel187 of the shuttle 146. The button 160 and the shuttle 146 can beconnected together in any suitable manner, including one or more offriction fit, snap fit, adhesive, etc. Once the button 160 and theshuttle 146 are connected, the button 160 is free to slide forward andrearward within the longitudinal channel 157 of the upper shell.

With reference again to FIG. 6F, the shuttle 146 further includes adownward protrusion, such as a wedge 184. The wedge 184 is configured tooperate on the lower plane of the interlock mechanism. In particular,the wedge 184 can be positioned between the proximal portions of thearms 171 a, 171 b of the gate 144. The wedge 184 can include cammingsurfaces that interact with the camming surfaces 174 a, 174 b of thegate 144 to urge apart the resiliently flexible arms 171 a, 171 b. Thewedge 184 can interact with the actuator stop 151 (FIG. 6A) to preventthe shuttle from traveling too far in a distal direction. In particular,the stop 151 may be positioned so as to ensure that a distal end of theactuation member 145 stops at a desired position relative to theactuated arms 108 a, 108 b (see FIG. 5C), such as, for example, aposition that is slightly proximal of the tissue engaging members 109 a,109 b of the actuated arms 108 a, 108 b. Such as position may, forexample, avoid pushing an engaged portion of the target tissue layer offof the actuated engaging members 109 a, 109 b.

With continued reference to FIG. 6F, the illustrated embodiment of theshuttle 146 includes a pair of laterally and proximally projectingresiliently flexible arms 185 a, 185 b. The arms 185 a, 185 b includestops 186 a, 186 b at the proximal ends thereof. The arms 185 a, 185 band stops 186 a, 186 b are positioned to operate on the upper level ofthe interlock mechanism. In particular, the arms 185 a, 185 b may beflexed inwardly as the actuator 148 is advanced distally to deploy thearms 108 a, 108 b via the actuation member 145 via contact with aportion of the hub 149, as discussed further below. Upon distaladvancement of the hub 149 to deploy the access device 147, however, thearms 108 a, 108 b can automatically return to a natural extended state,at which point the stops 186 a, 186 b engage the stops 159 a, 159 b ofthe upper shell 141. The shuttle 146 can be retained in this positionuntil the hub 149 is returned to a proximal position to free the stops186 a, 186 b from the stops 159 a, 159 b, as discussed further belowwith respect to FIG. 7E.

FIG. 6G depicts the access assembly 139, which includes the accessdevice 147 or piercing member and the hub 149. A proximal end of theaccess device 147 can be coupled to a body 191 of the hub 149 in anysuitable manner. The access device 190 can define a lumen 190 throughwhich communication with a region beneath the target tissue layer (e.g.,the pericardial space) can be established once the access device 147pierces through the target tissue layer. For example, a guide wire maybe delivered through the lumen 190.

The hub 192 includes a neck 192 that is shaped to fit within the keyslot defined by the keying surfaces 153 a, 153 b of the lower and uppershells 142, 141. The neck 192 can include outwardly projecting flangesthat, in cooperation with the keying surfaces 153 a, 153 b, preventrotational movement of the hub 149 about a longitudinal axis thereof.

The hub 192 can include a grip 197, which may be positioned proximal ofthe neck 192. The grip 197 can be sized and configured to be readilymanipulated by a user, such as by using a second hand while the userholds the housing 140 with a first hand. In the illustrated embodiment,a medical connector 198 is positioned at a proximal end of the hub 192.Any suitable connection interface is contemplated for the medicalconnector 198, which can serve to couple the hub 149 with any suitablemedical device(s) or equipment for delivering and/or withdrawing fluidto/from a region accessed by the distal end of the access device 147. Inthe illustrated embodiment, the connector 198 comprises a Luer fitting199.

With continued reference to FIG. 6G, the hub 149 includes three distallyprojecting tines, prongs, or arms 193, 194 a, 194 b. In the illustratedembodiment, the arms 193, 194 a, 194 b substantially form a tridentshape. The central arm 193 is shorter than the outer arms 194 a, 194 band includes a stop 195 at a distal end thereof. The stop 195 operatesat the lower level of the interlock system, and is configured tointeract with the stops 175 a, 175 b of the gate 144.

An upward protrusion 196 a, 196 b is positioned at the distal end ofeach of the side arms 194 a, 194 b. The protrusions 196 a, 196 b arepositioned to operate at the upper level of the interlock system. Inparticular, the protrusions 196 a, 196 b are configured to bend theproximal ends of the arms 185 a, 186 a inward when the hub 149 is drawnproximally to a retracted state, thereby permitting proximal movement ofthe shuttle to a retracted state, as shown in and discussed further withrespect to FIG. 7E.

Some of the features of the illustrated actuation mechanism 137 includea pair of elements to accomplish a given function. For example, the twoarms 185 a, 186 a interact with the two stops 159 a, 159 b to preventretraction of the actuation member 145 under certain conditions. Inother embodiments, only a single set of interacting features may beused. In some instances, however, a redundant set of interactingfeatures can provide strength, stability, and/r balance to the systemand/or act a as a backup or failsafe.

FIGS. 7A-7E demonstrate various stage of operation of the actuationmechanism 137. Many details regarding these stages of operation havealready been provided. FIGS. 7A-7E and the discussion that follows areto provide further clarity regarding to the manners in which the variouscomponents interact (e.g., to achieve a dual interlock mechanism).Certain features that were discussed with respect to at least FIGS.5A-6G may not be repeated in the following discussion, as the purpose ofthe present discussion is to provide a streamlined understanding of theillustrated actuation mechanism 137. The further details disclosed withrespect to at least FIGS. 5A-6G are fully applicable here, but will beomitted for the sake of brevity and clarity.

FIG. 7A is a cross-sectional view of the tissue engagement device 130along the view line 7A-7A in FIG. 1, as coupled with the tunnelercannula 110, which is also shown in cross-section. This drawing depictsthe shuttle 146 in a fully retracted configuration. Correspondingly, thedrawing depicts the actuation member 145 in the retracted configuration.Likewise, the access device 147 and the hub 149 are in the retractedconfiguration. Accordingly, the tissue engagement device 130 is in thefully retracted configuration. FIG. 7A corresponds with the view of thedistal end of the tissue engagement device 130 depicted in FIG. 5B. Inthis operational state, the gate 144 is closed and interacts with thecentral prong 193 of the hub 149 to prevent deployment of the accessdevice 147.

In FIG. 7B, the tissue engagement device 130 is in a partially deployedstate. In particular, the shuttle 146 has been advanced distally, butnot yet to its distal-most orientation. That is, the shuttle 146 hasbeen advanced to an intermediate phase of deployment. The gate 144 hasbegun to open, but is not yet open sufficiently wide to permit thedistal passage of the central prong 193 of the hub 149.

FIG. 7C depicts the actuation mechanism 137 of the tissue engagementdevice 130 in another partially deployed state. In this state, theshuttle 146 has been advanced to its distal-most position, and is thusfully deployed. However, the hub 149 and the access device 147 remain intheir retracted state. The full distal movement of the shuttle 146 hasopened the gate 144 to create the passageway 176, which is nowsufficiently large to permit passage of the central prong 193 of the hub149 in a distal direction. FIG. 7C corresponds with the view of thedistal end of the tissue engagement device 130 depicted in FIG. 5C.

FIG. 7D depicts the actuation mechanism 137 of the tissue engagementdevice 130 in a fully deployed state. Specifically, the shuttle 146 andthe actuation member 145 are in their distal-most orientations, and thehub 149 has been moved distally to at least partially deploy the accessdevice 147.

In this operational mode, the hub 149 is able to move distally andproximally in an unconstrained manner, or at least unconstrained withina range permitted by the confines of the housing 140. Unconstraineddistal movement permits a user to select the amount of force to beapplied to the access device 147 to pierce the target tissue layer, aswell as the distance (within a limited range) to which the access device147 will be inserted through the tissue layer.

Unconstrained proximal movement can be an advantageous safety feature,in some instances. For example, if a user inserts the access device 147through the tissue layer, but then becomes distracted or otherwiseinadvertently releases the hub 149, the underlying layer can beprotected from damage, such as by pushing the access device 147 in theproximal direction. In the context of pericardial access, for example, adistal tip of the access device 147 may be readily pushed rearward bythe beating heart if the practitioner maintains a grip on the housing140, but releases a grip on the hub 149.

Movement of the hub 149 and its upward protrusions 196 a, 196 b in thedistal direction releases the arms 185 a, 185 b of the shuttle 146 toautomatically resiliently expand outwardly into contact with the sidesof the housing 140. The proximal ends of the arms 185 a, 185 b come intocontact with the distal faces of the stops 159 a, 159 b, which preventsthe shuttle 146 from moving distally in the present configuration.

FIG. 7E depicts the actuation mechanism 137 in a partially deployedstate again, with the hub 149 having been withdrawn distally to aconfiguration that permits retraction of the actuation member 145.Moreover, movement of the hub 149 and its upward protrusions 196 a, 196b in the proximal direction compresses the arms 185 a, 185 b of theshuttle 146 to be displaced inward and out of contact from the distalfaces of the stops 159 a, 159 b. This configuration permits proximalmovement of the shuttle 146 to draw the actuation member 145 into theretracted position.

FIGS. 8A-8K depict various stages of illustrative methods for engaging atarget tissue layer and accessing a space beneath the same. Many detailsregarding these method stages have already been provided. FIGS. 8A-8Kand the discussion that follows are to provide further clarity regardingto the methods. Certain features that were discussed with respect to atleast FIGS. 5A-7E may not be repeated in the following discussion, asthe purpose of the present discussion is to provide a streamlinedunderstanding of the illustrated method stages. The further detailsdisclosed with respect to at least FIGS. 5A-7E are fully applicablehere, but will be omitted for the sake of brevity and clarity.

One illustrative method includes each stage depicted in FIGS. 8A-8K inthe sequential order shown. In the illustrative method, the pericardialspace of the heart of a patient is accessed. Other methods arecontemplated, including some that do not employ each method stageillustrated and/or that use additional stages. Moreover, other suitablecontexts (e.g., target tissue layers other than the pericardium) arecontemplated.

FIG. 8A depicts an early stage of an illustrative method for accessing aregion beneath a tissue layer. In particular, the method is used toaccess the pericardial space 53 between the pericardium 51 and theepicardium 52 of the heart 50 of a patient P.

In the illustrated method, the tunneling assembly 101 is provided, suchas by being removed from sterile packaging. In some embodiments, theobturator 120 and the tunneling cannula 110 are provided in apreassembled state. In other instances, an earlier stage of the methodinclude coupling the obturator 120 to the tunneling cannula 110 into theconfiguration show.

In some embodiments, an anterior approach may be used in directing thetunneling assembly 101 toward the heart 50. In other embodiments, aninferior or posterior approach is used, which can require passing thetunneling assembly 101 through the diaphragm. Such an approach may alsoreferred to as a transdiaphragmatic or subdiaphragmatic approach. Eachsuch approach may be referred to as a subxiphoid approach. The differentapproaches may result in different angles relative to the heart. Instill further instances, an intercostal approach, e.g., between the 6thand 7th ribs may be used and may provide direct access to differentareas of the heart. In some instances, the intercostal space allows theapex of the heart to be accessed, and so such an approach is also calleda transapical approach.

In view of the foregoing, a number of different approaches to the heartare contemplated. The tissue engagement systems 100, 102 and tissueengagement devices 130 disclosed herein can be particularly well suitedfor any such approach to the heart. In particular, the systems 100, 102and devices 130 can be particularly well suited to engage, grasp, pull,and or otherwise manipulate the pericardium 51 at any number ofdifferent approach angles. For example, the tissue engagement devices130 can work effectively at shallow angles of approach or steep anglesof approach. Indeed, certain embodiments are capable of functioning wellat approach angles of from 0 degrees (e.g., a fully transverseorientation) through 90 degrees (e.g., a fully orthogonal orientation).With respect to a 0-degree approach, a distal end of the device 130 cancome into contact with the pericardium and create a ripple, or asubstantially vertical (or upwardly extending) wall of tissue ahead ofthe distal end of the device. This phenomenon is similar to pushing apiece of fabric along a tabletop using a finger to generate a ripple orwave response. A local wave or ripple can create an at least somewhattransverse surface, relative to a distal end of the device 130, to whichthe tines can engage (e.g., grasp, grab, embed within, snag, catch,etc.)

FIG. 8B depicts a stage at which the tunneling assembly 101 has beenadvanced through an incision 56 in the skin 55 of the patient. The blunttip 122 of the obturator 120 has been urged through the connectivetissue 54 of the patient P into contact with an external surface of thepericardium 51.

FIG. 8C depicts a stage at which the obturator 120 is decoupled from thetunneling cannula 110 and removed therefrom. The tube 111 portion of thetunneling cannula 110 is left in the tissue 54 to provide a channel tothe pericardium 51.

FIG. 8D depicts a stage in which the tissue engagement device 130 iscoupled with the tunneler cannula 110. In particular, the sheath 131 isadvanced through the tube 111 and toward the pericardium 51.

FIG. 8E depicts another stage in which the tissue engagement device 130is in the fully retracted configuration, such as that of FIGS. 5B and7A, with the tissue engagement members 109 a, 109 b (e.g., the distaltips) of engagement arms 108 a, 108 b positioned at the target tissuelayer, which in this instance is the pericardium 51. The tissueengagement device 130 is fully coupled with the tunneler cannula 110.

FIG. 8F depicts another stage in which the tissue engagement device 130is in the partially deployed state, such as that of FIG. 7B, with theactuation member 145 advanced distally to an intermediate position toembed the tissue engagement members 109 a, 109 b arms in the pericardium51. In the illustrated embodiment, the tissue engagement members 109 a,109 b do not extend through a full thickness of the pericardium 51 topass into the pericardial space 53. Stated otherwise, the engagementmembers 109 a, 109 b do not pass through an interior or bottom surfaceof the pericardium 51. This can result from the initial shallow angle ofthe engagement members 109 a, 109 b relative to the pericardium 51, andfurther, from a shallow deployment path for each of the engagementmembers 109 a, 109 b. By “shallow deployment path,” it is meant that thepath traced by the engagement members 109 a, 109 b (e.g., a distal tipthereof) extends only a small longitudinal distance from the distal endof the actuation member 145, or from the starting point of therespective engagement member 109 a, 109 b. In various embodiments, eachengagement member 109 a, 109 b progresses distally from its staringpoint to a maximum longitudinal distance (i.e., a distance as measuredonly in the longitudinal direction, or in a direction that is collinearwith or parallel to a longitudinal axis of the actuation member 145)that is no greater than 1, 2, 3, or 4 millimeters. Indeed, in someembodiments, an entirety of the path traced by each engagement member109 a, 109 b may have no longitudinal component (e.g., may be entirelylateral), or may have a longitudinal component that progresses only inthe proximal direction, or stated otherwise, only moves laterally andproximally from the starting point.

In various embodiments, each engagement member 109 a, 109 b defines amaximum length. For example, in the illustrated embodiment, the maximumlength of each engagement member 109 a, 109 b is the distance from thedistal point thereof to a primary bend (e.g., the only bend in each arm108 a, 108 b that is readily apparent in FIG. 8F). In variousembodiments, each engagement member 109 a, 109 b progresses distallyfrom its starting point to a maximum longitudinal distance that is nogreater than 0.25, 0.5, 0.75, 1, 1.25, or 1.5 times the maximum lengthof the engagement member 109 a, 109 b.

It may alternatively be stated that each engagement member 109 a, 109 bfollows a deployment path that is substantially transverse to thesurface of the target tissue layer. The substantially transversedeployment of the engagement members 109 a, 109 b can embed theengagement members 109 a, 109 b within the tissue layer and can put thetissue layer under tension in the transverse direction. A substantiallytransverse deployment path also reduces the risk of contacting and/ordamaging an underlying tissue layer, such as the epicardium 52.

In other embodiments, at least a portion of one or more of theengagement members 109 a, 109 b may extend through a full thickness ofthe target tissue layer. Stated otherwise, in other embodiments, theengagement members 109 a, 109 b may pierce through the bottom or innersurface of the tissue layer.

In some embodiments, the each of the engagement members 109 a, 109 bdefines an angle relative to a distal projection of longitudinal axis ofthe device 130. In various embodiments, this angle can be no less than60, 70, or 80 degrees throughout movement of the actuation cannula 145from the retracted position to the extended position.

FIG. 8G depicts a stage in which the tissue engagement device 130 is inthe further partially deployed state, such as that of FIGS. 5C and 7C,with the actuation member 145 advanced to the distal-most position tofurther embed the engagement members 109 a, 109 b in the pericardium 51.In the illustrated embodiment, the engagement members 109 a, 109 bextend laterally outward at an angle of approximately 90 degreesrelative to the adjacent, proximal portions of the arms 108 a, 108 b.Other angles relative to the arms 108 a, 108 b in this fully deployedstate are also contemplated, as further discussed below.

FIG. 8H depicts a stage in which the tissue engagement device 130 is inthe same configuration as that depicted in FIG. 8G and in which thetissue engagement device 130 is drawn proximally to enlarge thepericardial space 53 between the pericardium 51 and the epicardium 52 inthe vicinity of the engagement members 109 a, 109 b. Such a separationevent may result in tenting of the pericardium 51 at the engagementposition. This tenting is shown only schematically in FIG. 8H, as thetenting can be quite steep in some instances, such as may result fromvacuum or other forces within the pericardial space 53 as thepericardium 51 is drawn upward in the manner shown.

FIG. 8I depicts a stage in which the tissue engagement device 130 hasbeen moved to the fully deployed state, such as that of FIGS. 5D and 7D,in that both the actuation member 145 and the access device 147 havebeen advanced distally. At the illustrated stage, the access device 147has pierced the pericardium 51 to provide access to the pericardialspace 53. Communication with pericardial space 53, such as for theintroduction or removal of fluid, can be achieved via the medicalconnector 198.

As discussed with respect to FIG. 8H, tenting in the vicinity of theactuation arms 108 a, 108 b may be quite steep. However, the regionbetween the arms 108 a, 108 b may be substantially planar due to tensionprovided by the arms 108 a, 108 b. The access device 147 thus may bereadily advanced through the portion of the pericardium 51 that is heldin tension, which is relatively unaffected by the neighboring tenting.

In particular, a distal end of the access device 147 may be pointed, orangled relative to a longitudinal axis of the device. As a result,insertion of the device 147 is much easier through a planar region thatis substantially orthogonal to the longitudinal axis of the device—e.g.,through the region between the arms 108 a, 108 b—than it is throughregions that have shallower angles relative to the tip, such as thesteep tented surfaces that surround the region that is held between thearms 108 a, 108 b. For this reason, it can be advantageous in someembodiments to ensure that a tip of the access device 147 passes througha line that extends between the arms 108 a, 108 b when the arms 108 a,108 b are in the deployed state.

FIG. 8J depicts a stage in which the tissue engagement device 130remains in the fully deployed state and a distal end of a guidewire 200has been advanced distally through the access device 147 into thepericardial space 53. The guidewire 200 may be of any suitable varietyor size. In various embodiments, a thickness of the guidewire can be0.035 inches (0.89 millimeters) or 0.032 inches (0.81 millimeters).

FIG. 8K depicts another stage in which the tissue engagement device 130has been returned to the partially deployed state, such as that of FIGS.5C and 7C. In particular, the access device 147 has been retracted. Fromthis stage, the actuation member 145 may subsequently be retracted andthen the device 130 can be removed from the patient P. The distal end ofthe guidewire 200 can remain in place within the pericardial space 53 asthe tissue engagement device 130 is withdrawn. Although the arms will bein a retracted state during removal of the device 130, positioning ofthe guidewire 200 will be relatively unaffected during withdrawal of thedevice 130. In particular, as the device 130 is withdrawn, the arms 108a, 108 b pass by the guidewire 200. State otherwise, the guidewire 200can pass through openings 225, 226 defined by the arms 108 a, 108 b,even though the arms 108 a, 108 b cover the distal opening of theactuation member 145. The openings 225, 226 can be seen, for example, inFIGS. 11C and 11D.

FIG. 9 depicts an embodiment of an engagement element 143 during a stageof a manufacturing process therefor. In the illustrated embodiment, theengagement element 143 is formed from a unitary piece of material. Anysuitable material is contemplated. The material can desirably exhibitthe properties described herein. In some embodiments, the engagementelement 143 is formed from a unitary piece of stainless steel that hasbeen formed as a tube.

Prior to the stage of the manufacturing method depicted in FIG. 9,portions of the tube are cut or otherwise removed to form the arms ortines 108 a, 108 b (the tine 108 b is hidden in FIG. 9, but is shown inother figures, such as FIG. 10A). In some embodiments, the tines arelaser cut. The tines 108 a, 108 b can extend distally from the remainingportion of the original tube, which is also referred to herein as thecannular base 104.

The tines 108 a, 108 b can each include a relatively wide base region210, which can extend distally from a distal end of the cannular base104. In various embodiments, a width of the base region 210 can be nogreater than about ⅔, ½, or ⅓ of a diameter of the cannular base 104.The base region 210 can have an angled step down to a displacementregion 212. The displacement region 212 of each arm is the region ofgreatest displacement during use. A thinner displacement region 212 canpermit a compact or low profile design. In particular, a thindisplacement region can be desirable where the tines 108 a, 108 b crossone another in the retracted orientation and move past each other duringdeployment. In various embodiments, a thickness of the displacementregion is no greater than about ½, ⅓, ¼, ⅙, or ⅛ of the diameter of thecannular base 104.

Removal of portions of the original tube can also yield a piercingsurface 214 a, 214 b (see also, e.g., FIG. 10A). In the illustratedembodiment, the piercing surfaces 214 a, 214 b are fashioned as pointedends or barbs at the distal tips of each tine 108 a, 108 b. An attackangle α of the piercing surfaces 214 a, 214 b can be selected to provideready engagement with the target tissue layer. In various embodiments,the attack angle α is no greater than about 10, 15, 20, 25, or 30degrees.

FIG. 10A is a side elevation view of the engagement element 143 afterfurther processing, and FIG. 10B is a top plan view thereof. In furtherprocess stages that result in the configuration depicted in FIGS. 10Aand 10B, the tines 108 a, 108 b are bent about multiple axes. In someembodiments, a primary bend 216 a, 216 b is made by rotating the distalend of the tines 108 a, 108 b about the y-axis. In particular, the tine108 a is rotated in a first direction about the y-axis, and the tine 108b is rotated in an opposite direction about the y-axis. In variousembodiments, an angle of plastic deformation that results from thebending can be within a range of from about 30 degrees to about 120degrees, from about 45 degrees to about 115 degrees, or may be no morethan about 45, 60, 90, or 115 degrees.

The primary bends 216 a, 216 b can yield the engaging members 109 a, 109b. Retention surfaces 219 a, 219 b at the proximal sides of the engagingmembers 109 a, 109 b may vary in effectiveness at holding the targettissue layer, depending on the angle of plastic deformation of the bends216 a, 216 b.

The tines 108 a, 108 b can be rotated and permanently bent in the samedirection about the z-axis. Additionally, or alternatively, the tines108 a, 108 b can be rotated and permanently bent in opposite directionsabout the x-axis. The latter bending may be referred to as splining, andcan permit the tines 108 a, 108 b to move past one another when anadditional permanent bend, or secondary bend 218 a, 218 b (FIG. 10) isformed.

As shown in FIG. 10B, in some embodiments, the tines 108 a, 108 b definea natural orientation in which the lateral width at a distal end of thetines 108 a, 108 b is greater than a diameter of the cannular base 104.As a result, when the tines 216 a, 216 b are received within the sheath131, which has an interior diameter that only slightly exceeds the outerdiameter of the base 104, the tines 108 a, 108 b are spring-loaded. Thatis, the tines 108 a, 108 b naturally attempt to assume the configurationshown in FIGS. 10A and 10B, but are prevented from doing so by thesheath 131 (see FIG. 5B). Providing such a pre-load to the tines 108 a,108 b allows them to naturally return to the constrained orientationdepicted in FIG. 5B after the actuation member 145 is retracted.

FIGS. 11A-11D depict various views of the engagement element 143 when inthe constrained configuration that is provided by the sheath 131, suchas in the arrangement depicted in FIG. 5B. For clarity, the sheath 131is not shown in these views. In this operative state, the tines 108 a,108 b cross each other at a position distal of the distal end of thecannular base 104. In this particular embodiment, the tines 108 a, 108 bcontact one another at a crossing point 220. Other embodiments may crossone another near a crossing point, but not contact each other thereat.The crossing point in such arrangements may be the midpoint of a minimumdistance between the tines 108 a, 108 b where they cross. As previouslymentioned, the tines 108 a, 108 b can define openings 225, 226 throughwhich a guidewire may readily pass during use.

As can be appreciated from the foregoing, in certain embodiments, thetines 108 a, 108 b can be positioned diametrically opposite one another.When in a retracted state, the tines 108 a, 108 b can be in asubstantially bent configuration. When actuated, a proximal portion ofeach tine 108 a, 108 b that is constrained within the sheath 131 can besubstantially straightened. The straightened tines may be substantiallyparallel to each other and/or substantially parallel to a longitudinalaxis of the cannular base 104. A length of each tine 108 a, 108 b may besufficiently long to prevent plastic deformation of the tines 108 a, 108b during deployment. The tines are formed in an elastically resilientfashion that permits them to automatically and naturally return to thepre-deployment state after deployment.

Further, as is clear from the foregoing disclosure, in some embodiments,the first and second piercing surfaces 214 a, 214 b are moved at anexterior of the sheath throughout transition of the actuation cannulafrom the retracted position to the extended position. In other orfurther embodiments, the actuation cannula 245 defines a longitudinalaxis, and the first and second tines 108 a, 108 b rotate about thelongitudinal axis as the actuation cannula transitions from theretracted position to the extended position. Stated otherwise, the firstand second tines 108 a, 108 b can progress toward their pre-bent stateduring actuation, and can return to their formed condition duringretraction.

With reference to FIGS. 12A and 12B, certain embodiments of theengagement element 143 can include a centering protrusion 230. In theillustrated embodiment, the centering protrusion 230 is an inwardlydirected bump 230 that is impressed into the cannular base 104. In otherembodiments, the centering protrusion 230 may instead be formed from adifferent material and fixedly secured to the inner wall of the cannularbase 104.

As shown in FIG. 13, the centering protrusion 230 constrains movement ofthe actuation member 145 (e.g., constrains lateral movements relative toa longitudinal axis), which in turn constrains movement of the accessdevice 147. This arrangement can ensure that a distal tip 240 of theaccess device 147 is substantially centered relative to the engagementelement 143. In some embodiments, during actuation of the access device147, the distal tip 240 can pass through a line L that extends throughthe distal tips of the tines 108 a, 108 b. Such an arrangement can aidin delivering the tip 240 through a portion of the pericardium that isbetween the tines 108 a, 108 b and is in tension due thereto. Forexample, this can permit the tip 240 to pass through a relatively flator plateaued region at the apex of a tented portion of the pericardium,as previously discussed.

As shown in FIGS. 14A and 14B, in some embodiments, the access device147 can be a needle 250 having a centered distal tip 240. In someinstances, the needle 250 is formed with a bevel 242 (e.g., one or moreof a bias grind, a lancet grind, etc.), and is then bent to move thedistal tip 240 into alignment with a longitudinal axis of the needle250.

FIGS. 15-20 depict another embodiment of a tissue engagement system 300that can resemble the tissue engagement systems discussed above in manyrespects. Accordingly, like features are designated with like referencenumerals, with the leading digits incremented to “3.” Relevantdisclosure set forth above regarding similarly identified features thusmay not be repeated hereafter. Moreover, specific features of the tissueengagement system 300 may not be shown or identified by a referencenumeral in the drawings or specifically discussed in the writtendescription that follows. However, such features may clearly be thesame, or substantially the same, as features depicted in otherembodiments and/or described with respect to such embodiments.Accordingly, the relevant descriptions of such features apply equally tothe features of the tissue engagement system 300. Any suitablecombination of the features and variations of the same described withrespect to the tissue engagement systems discussed above can be employedwith the tissue engagement system 300, and vice versa.

Referring to FIG. 17, the system 300 for engaging a tissue layer and forproviding access to a region beneath the tissue layer includes a tissueengagement element 343 having a cannular base or housing 304 withintegrated tissue engaging members 308 a, 308 b, and a cannula 345 toactivate the tissue engaging members 308 a, 308 b within the lumen ofthe housing 304, and a tissue piercing member 347 within with lumen ofthe cannula 345, to secure access to the region beneath the tissuelayer.

Referring to FIG. 15 there is depicted an embodiment of a system 300with the cannula 345 and the tissue piercing member 347 retracted withinthe housing 304, such that the cannula 345 and the tissue piercingmember 347 are not in contact with the tissue engaging members 308 a,308 b.

Referring to FIG. 16 there is shown an embodiment of the housing 304with the tissue engaging members 308 a, 308 b fully deployed. The distalend of the cannula 345 is advanced to the distal end of the housing 304,thereby causing the tissue engaging members 308 a, 308 b to deployoutward.

Referring to FIG. 18 there is shown an embodiment of the system 300,with the distal end of the cannula 345 advanced from the proximal end310 a of the tissue engaging member 308 a to the distal end of thehousing 304, thereby deploying the tissue engaging member 308 a. Thetissue engaging member 308 b is deployed in like manner. The tissuepiercing member 347 is advanced beyond the distal end of the housing304.

Referring to FIG. 19 there is shown a front view of one embodimentdepicting the offset nature of the tissue engaging members 308 a, 308 bat the distal end of the housing 304.

Referring to FIG. 20 there is depicted a side view of the engagement ofa tissue layer 51 by the tissue engaging members 308 a, 308 b, and thedeployment of the tissue piercing member 347 into the space under thetissue layer 51.

As shown in these drawings, the illustrated system 300 includes anelongated housing 304, which may also be referred to as a cannula,having a proximal and distal end. The distal end terminates at a distaltip of the needle 347 when said needle 347 is extended as in FIG. 17 andthe distal end terminates at the distal tip of the housing 304 when saidneedle 347 is retracted as in FIG. 15. The needle 347 can be advanced toaid insertion into the patient skin as in FIG. 17, and then retracted asin FIG. 15 as the device 300 is moved towards the tissue layer 51 to beengaged, to reduce damage to tissues that could be caused by an extendedneedle. The illustrated embodiment is particularly well suited forproviding access to the pericardial space using a subxiphoid approach.The non-deployed tissue engaging members 308 a, 308 b as shown in FIG.15 may effectively pass through soft tissue of a patient untilcontacting the pericardium, and can be sufficiently blunt to inhibitpuncture or piercing of the pericardium or other tissues when advanced.

The housing 304 may be formed of any suitable material. In someembodiments, the housing 304 is metallic, whereas in other or furtherembodiments, the housing 304 can be formed of a substantially rigidplastic.

The needle 347 may be formed of any suitable material. For example, insome embodiments, the needle 347 is formed of stainless steel. Thematerial is chosen such that it is sufficiently rigid to pierce thetissue layer.

The cannula 345 may be formed of any suitable material. For example, insome embodiments, the cannula 345 is formed of stainless steel. Thematerial chosen such that is sufficiently rigid and strong to deploy thetissue engaging members 308 a, 308 b.

During use of the system 300, the needle 347 may be extended past thehousing 304 to be inserted into a patient to the desired location, andthe proximal end of the housing 304 can remain at an exterior of thepatient. In one embodiment, the system is inserted into the patient withthe needle 347 in the retracted position as shown in FIG. 15 via anincision in the patient at the desired location. In some embodiments,the system 300 includes one or more actuators at the proximal end bywhich a user can deploy the needle 347 and/or the cannula 345. Anysuitable actuator arrangement is possible. In other or furtherembodiments the cannula 345 and the access needle 347 may be manipulateddirectly by a user and advanced through the housing 304 without relyingon any actuators.

In one embodiment, the system 300 comprises a first actuator at theproximal end of the system that is configured to deploy and/or retractthe needle 347. While any suitable actuator arrangement is contemplated,the illustrated actuator comprises a button, switch, tab, or protrusionthat is coupled to a proximal portion of the needle 347. In theillustrated embodiment, a relatively large annular space is depictedbetween an exterior surface of the access needle 347 and an interiorsurface of the cannula 345 and the interior surface of the housing 304.In some embodiments, this annular space is proportionally much smaller,minimized, or substantially eliminated. For example, a snug fit, a loosefit, or a minimal gap may be provided between at least a portion of aninterior surface of the sidewall of the housing 304 and at least aportion of an exterior surface of the cannula 345, and the access needle347, which can desirably reduce an overall diameter (e.g., maximumcross-sectional width, where the cross-section is not necessarilycircular) of the system 300, or more particularly, an outer diameter ofthe housing 304. Such an arrangement also can reduce or avoid coring oftissue by the housing 304 as the system 300 is advanced into a patient.

FIG. 20 depicts the distal end of the system 300 as having been advancedinto the patient and as having engaged the tissue layer 51. The tissuelayer 51 is pulled back and the needle 347 is advanced into the spacecreated under the tissue layer 41. A guidewire may be advanced throughthe lumen of the tissue piercing layer into the space under the tissuelayer.

With reference again to FIG. 18, it is preferable that the length of thetissue engagement member 308 a, 308 b as it extends along the housing304 is sufficiently long to prevent plastic deformation of the tissueengagement member 308 a, 308 b during actuation by the cannula 345.

With reference again to FIG. 19, the shape of the distal end of thetissue engagement members 308 a, 308 b are sharp such that they can cutinto the tissue layer 51. The prongs are sufficiently long to engage thetissue layer 51, but they are not longer than the diameter of thehousing 304, such that they do not extend beyond the border of thehousing 304 when non-actuated as shown in FIG. 15. The prongs thatengage the tissue layer may be bent at 90 degrees as shown, or they maybe bent between 60 degrees to 120 degrees to enable tissue engagementand retention. The sharp tip of the prong may be cut from the center asshown, or it may be cut a variety of angles, or it may not be cut at anyangle, to enable tissue engagement and retention. The prong profile andsharpness are designed to engage the tissue layer 50 at a low angle or ahigh angle. This allows for low and high approach angles, butparticularly low-angles that can be particularly suitable for alow-angle, subxiphoid approach to the heart, for example.

With reference again to FIG. 15 and FIG. 19, the tissue engaging members308 a, 308 b may be offset as shown, or they may not be offset such thatthey do not pass each other during activation by the cannula 345. Thelength of the prongs at the distal end of the tissue engaging members308 a, 308 b constructed such that they do not extend beyond thediameter of the housing 304 when not activated by the cannula.

Any methods disclosed herein comprise one or more steps or actions forperforming the described method. The method steps and/or actions may beinterchanged with one another. In other words, unless a specific orderof steps or actions is required for proper operation of the embodiment,the order and/or use of specific steps and/or actions may be modified.

References to approximations are made throughout this specification,such as by use of the terms “about” or “approximately.” For each suchreference, it is to be understood that, in some embodiments, the value,feature, or characteristic may be specified without approximation. Forexample, where qualifiers such as “about,” “substantially,” and“generally” are used, these terms include within their scope thequalified words in the absence of their qualifiers. For example, wherethe term “substantially planar” is recited with respect to a feature, itis understood that in further embodiments, the feature can have aprecisely planar orientation.

Any reference throughout this specification to “certain embodiments” orthe like means that a particular feature, structure or characteristicdescribed in connection with that embodiment is included in at least oneembodiment. Thus, the quoted phrases, or variations thereof, as recitedthroughout this specification are not necessarily all referring to thesame embodiment or embodiments.

Similarly, it should be appreciated that in the above description ofembodiments, various features are sometimes grouped together in a singleembodiment, figure, or description thereof for the purpose ofstreamlining the disclosure. This method of disclosure, however, is notto be interpreted as reflecting an intention that any claim require morefeatures than those expressly recited in that claim. Rather, as thefollowing claims reflect, inventive aspects lie in a combination offewer than all features of any single foregoing disclosed embodiment.

The claims following this written disclosure are hereby expresslyincorporated into the present written disclosure, with each claimstanding on its own as a separate embodiment. This disclosure includesall permutations of the independent claims with their dependent claims.

Recitation in the claims of the term “first” with respect to a featureor element does not necessarily imply the existence of a second oradditional such feature or element. Elements specifically recited inmeans-plus-function format, if any, are intended to be construed inaccordance with 35 U.S.C. § 112(f). Embodiments of the invention inwhich an exclusive property or privilege is claimed are defined asfollows.

1. A method comprising: engaging the pericardium of a patient with firstand second arms of a tissue engagement device; tensioning a portion ofthe pericardium by separating at least a portion of each of the firstand second arms from each other while the first and second arms continueto engage the pericardium; and after said tensioning, advancing anaccess device through the tensioned portion of the pericardium tointroduce the access device into the pericardial space of the patient.2. A method comprising: engaging the pericardium of a patient at twoengagement positions of the pericardium; moving the two engagementpositions of the pericardium away from each other to tension a portionof the pericardium; and advancing an access device through the tensionedportion of the pericardium to introduce the access device into thepericardial space of the patient.